The present invention relates to a service unit for servicing a refrigeration circuit and particularly to a system for assuring a supply of refrigerant remains available during the automatic servicing cycle.
Portable carts are used in connection with servicing refrigeration circuits, such as the air conditioning unit of a vehicle. The portable machines are coupled to the refrigeration circuit to be serviced and vacuum pumps and compressors operate to recover refrigerant from the vehicle's air conditioning unit, separate contaminants and oil from the recovered charge, flush the unit, and subsequently recharge the system from a supply of either recovered refrigerant and/or new refrigerant from a main refrigerant tank. U.S. Pat. No. 4,441,330 discloses one such apparatus.
In the past, when the supply of refrigerant would run low, a display system associated with the equipment would prompt the operator to connect an external tank and refill the refrigerant supply. This resulted in a time-consuming and potentially error-prone system by which a servicing cycle can be interrupted by the lack of adequate refrigerant or refrigerant could inadvertently escape to the atmosphere during the refilling of the refrigerant supply tank.
Thus, there exists a need for a system by which the supply of refrigerant employed for recharging a refrigerant circuit, such as a vehicle air conditioning unit, can be maintained at a serviceable level during use and without operator intervention.